This invention relates in general to semi-automated dara acquisition systems and more particularly, to systems for reading digital data stored on cards.
Numerous forms of cards having digital data stored thereon are known in the art. Examples of such cards are credit cards having a customer account number, Hollerith encoded tab cards, and employee badges, which may typically include employee data such as employee number, shift number, and pay grade. The dimensions and data format of such badges are presently being standardized by the Credit Card Standard Committee of the American Standards Institute.
The digital data may be stored on such badges or cards in one of many forms. For example, raised areas on the badge or card may be used to denote a data bit (for use with mechanical reading systems employing static contacts). Such mechanical systems are, however, relatively unreliable in that the contact elements are subject to physical damage from repeated use. In other forms, the data words may be encoded by positioning an optically reflective area on the card in an appropriate field to represent a data bit (for use with optical reading systems employing light source and sensor configurations). Alternatively, a hole may be punched in the card in an appropriate field to represent a data bit (for use with optical reading systems employing a light source on one side of the card and a sensor element on the other side). Still other forms might include magnetically encoded data bits (for use with magnetic reading systems).
In each of these cases, the data stored by the card may include a multiple character data word in the form of a rectangular M row .times. N column data matrix with each column comprising an encoded character of the stored word. For example, a 10 digit decimal number may be encoded by a 10 .times. 10 data matrix wherein the binary words formed by the 10 bits of the columns are representative of the correspondingly positioned digits or characters of the data word.
Generally, readers for such cards include an array of data detection elements with the individual elements disposed at locations corresponding to the bit locations of the data matrix on the card to be read. When a card is inserted in the card reader and maintained at a fixed position with the data matrix aligned with the detection element array, a reading operation may take place. Thus, in such systems, the detection element array includes a data detection element for each potential bit in the data matrix, e.g., where the data matrix includes ten characters, each having 10 bits, 100 detection elements are required to detect the data word. In addition, the card reader must include means for maintaining the card in a position aligning the data matrix with the detection element array for a duration sufficient for reading.